The existing Lionel RS-3 is definitely intended for the toy train world, but it is scale length, not traditional.
The Weaver RS-3 was definitely a scale model, but not a very robust frame. It would be interesting to see if Lionel ever uses it, but I still don’t know where this information is that says Lionel bought the tooling for Weaver’s GP38 and RS-3. I know Lionel bought the tooling for some of the freight cars and Atlas bought some locomotive and rolling stock tooling because I read press releases on those in 2015 and 2016.